Thermal responsive noise suppressor for exhaust duct

Abstract

An exhaust duct for a thrust jet engine, such as a rocket or gas turbine, which an acoustic and/or thermal protection lining is situated coaxially within a support element of the duct and is deformable radially relative to the support member, and preferably also adapted for relieving axial differential expansion stresses between the lining and the support element.

We claim: 
     
       1. A thrust jet engine exhaust duct comprising a tubular support element, at least three annular lining sections disposed successively and coaxially within and radially spaced from said support element, means for connecting the first lining section rigidly to said support element at a first location in said duct, first connector means for connecting the last lining section rigidly to the support element downstream of said first lining section, second connector means for connecting the ends of the at least one remaining lining section to the adjacent ends of the successive lining sections to permit axial displacement and radial deformation of the lining sections so connected, and third connector means connecting said at least one remaining lining section to said support element to permit radial displacement of said at least one remaining lining section with respect to said support element. 
     
     
       2. A jet exhaust duct as claimed in claim 1 wherein said second connector means includes bell-shaped portions formed at the trailing and leading ends respectively of said first and last lining sections for engaging the adjacent ends of the at least one remaining lining section and wherein the leading and trailing ends respectively of said first and last lining sections are rigidly connected to said support element. 
     
     
       3. A jet exhaust duct as claimed in claim 2 wherein said second connector means further includes annular swivel flange means formed at the leading and trailing ends of the at least one remaining lining section for engaging the bell-shaped portions at the adjacent ends of the first and last lining section. 
     
     
       4. A jet exhaust duct as claimed in claim 1 wherein said third connector means includes a part-spherical swivel means disposed intermediate the ends of each of the at least one remaining lining section, a stud engaged with said swivel means, a connecting rod affixed intermediate its ends to said stud, articulation means connecting one end of said connecting rod to said support element, a bracket means affixed to said support element and axially spaced from said articulation means, a connecting link articulated at one end to said bracket and at the other end to said connecting rod whereby differential expansion of said at least one remaining lining section with respect to said support element is compensated for. 
     
     
       5. A jet exhaust duct as claimed in claim 1 wherein there are three successive annular lining sections. 
     
     
       6. A jet exhaust duct as claimed in claim 1 wherein said lining sections have a thickness not greater than 1.5mm and include perforations therethrough, each perforation having a diameter of about 2mm and wherein the total area of said perforations is from about 10% to about 20% of the total area of said lining sections. 
     
     
       7. A jet exhaust duct as claimed in claim 1 wherein said annular lining sections are spaced from said support element a distance of substantially 35 mm.